Electrical switch



rJaln. 26, 1.9432. P. s. .nahmn'qs 1,842,453

ELECTRICAL SWITCH Original Filed April 21, 1925 f 4 Sheets-Sheet l Jan. 26, 1932.

P. S. JENKINS ELECTRICAL SWITCH Original Filed April 2l, 1923 X 4 Sheets-Sheet 2 COVE/7 CLOSED 5W/TCH OPEN CUI/Ef? CLOSE@ .SW/TCH CLOSED `lan. 26, 1932. P, s, JENKINS 1,842,453

ELECTRICAL SWITCH Original Filed April 21, 1925 4 Sheets-Sheet 5 COVE?? OPE/V 5W/TCH 62,0550

IKM/907168) jig@ Jan. 26, 1932.

P. `s. .JENKINS ELECTRICAL SWITCH Original Filed April 21, 1923 4 Sheets-Sheet 4 v,410. JROML@ Patented Jan. 26, 1932 UNITED .STATES PATENT OFFICE `PATTI.Y S. JENKINS, OF DETROIT, MICHIGAN, ASSIGNOR TO SQUARE D COMPANY, O 'DETROIL MICHIGAN, A CORPORATION 0F MICHIGAN ELECTRICAL SWITCH Application led` April 21, 1923, Serial No. 633,580. Renewed October 27, 1928.

in part of my copending application, Serial No. 505,989, filed October 7, 1921, in so far as it involves common subject-matter. It will be later observed `that the interlock, which has been illustrated in said copending applicat-ion, is also illustrated herein, but with cer- 120- tain additions thereto, in order to increase its utility, and so that it maybe universally usedand standardized -in switches of any size-or capacity/.

With the development of electric power in recent years, the use of safetyA switches has become quite pronounced. The advantages which are obtained from the .use of these switches are numerous and at the `present 'time `need littlepex'planation, especially inl view of the disclosure in the aforesaid copending application. Some 'meansmust Ybeprovided whereby the unskilled workman may be protected from coming into contact -.withlive circuits.' In the above identified copending applicatiomfan interlock yhas been illustrated, which cooperates with the switch operating means, for locking the cover closed while the switch is closed, or the switch open While the cover is open. I have found this 4o mechanism to be very eilicient and satisfactory, having Vmet with remarkable success on the market. 4However,` its universal application to switches irrespective of capacity or size has presented adiiiicult problem. The

y difficulty has been in. devising an interlock of proper size which could be aptly used on any size'switch without being too weak, or too strong-or too cumbersome, for the particular switch in'question. Take for example, a 60 lswitch of a capacity o f 200 amperes or over,

l Apering with the switch in open position when the cover is open, and to prevent them from opening the cover before the switch is opened. With reference to the first requirement, it is evident that should the cover be opened, the switch might be closed by jamming'the interlock mechanism, providing the latter could be jammed. This will, of course, depend upon the size ofthe switch, particularly the operating member. If the moving parts of ythe 'switch are large and heavy, little trouble would be experienced in an 'attempt to jam the interlock mechanism. Hence an interlock mechanismof insufficient strength falls short of accomplishing the desired'result, as it could not be relied upon to safeguard againstthe unauthorized acts of those for whom this type of switch yis especially provided.

It must not be forgottenthat a disabling device is contemplated, in connection with the present interlocking mechanism, in order to render the interlock ineffective, by the proper person, when desired. This disabling device has also been full)7 disclosed in said copending application, and has become standard equipment onl safety switches provided with interlocking mechanism. To this end,

'th'e implement used to operate this disabler has been designed in the form of a standard key' which may be used universally on switches of man types and sizes. The advantage of thisv eature is obvious when it is borne in mind that many large industrial plants use hundreds of these switches, and to` require a different key for each switch would be a useless duplication and waste of material, aswell as troublesome for the inspector in charge. It has, therefore, been the aim of manufacturers ofk switches to aov I 2 5 .y i 1,842,455.

y standardize their interlocking mechanism, in

order to permit the universal use of a single key, and-thereby avoid the above objections.

Coming now to the advantages of standardizin the interlocking mechanism, as well as the 'sabler and key therefor, in view of what has been said, it will be observed that this can be readily accomplished if mechan- V Y ism of standard size is adopted and added provision made for the larger size switches.

However, should an attempt be made to pro-` vide the interlocking mec anism in-various sizes considerable diiiculty would be experienced. Among them would be the requirement for a heavy investment in dies and tools, and furthermore, diiculty would be encountered in designing the parts so that the standdard disabling key could be used. Notwith-l standing all this, the mechanism would, perforce, become more intricate, -as the parts would have to be made more substantial. I have found that an attempt along this line would require the interlocking mechanism to be Abuilt in many sizes, inasmuch as one capable of being used on a switchof. 200 amperage capacity` would be, by far, too small. for.'

a 1200 ampereswitch.

As beforel pointed out, according to the teachings of my invention, I provide a standard size interlocking mechanism, preferably large enough for the smaller switches. The

switch Acoo erates with the interlocking mechanism by means of a toggle rod, or like element. When the switch is'of a larger size, or of such size that suiiicient force can be placed in-back of the effort close the switch i while the cover is open, by ]amm ing or Vpermanentl disablin the interlocking mechanism,"I ave foun that the strain upon the toggle rod will cause rupturing of thismechanism or breaking of the rod.

Broadly, therefore, it is "an object of my 1nvention to reinforce this toggle rod, or connecting element, and also the interlocking mechanism. This' is accomplished by the provision offa relay connection between the 'switch operating member and interlocking mechanism, so that when the cover is opened a barrier or like member 'may be inserted in the path of the switch operating member to prevent its movement. i

A-further object vof myf-invention is to so relate the relay connection `with the inter- I locking` mechanism that it will not be necessary to change the design or construction of the latter,A 'but on the contrary embody it, in its unitary relation, within the switch 'the same as in smaller capacity switches. I consider this feature important, as it allows standardization of the interlocking mecha- Incidental to the above vadvantage ofemployin'g a 'standard interlocking mechanism and the use of the relay connection therewith in larger capacity switches, the interlocks thereby provided Imay be disabled when desired so that the 4switch can be closed while the cover is open. This is' accomplished by the use of a disabler in conjunction with the interlocking mechanism, and inasmuch asin the present case, I intend connecting the relay connection with the interlocking mechanism in order that it will be controlled thereby, the rendering of the interlocking mechanism ineffective will automatically render the relay connection ,inefl'ective .Another object of my invention is to provide an improved toggle mechanism whereby the added inertia of larger switches may be overcome by` the use of a double spring toggle to insure a quick make and break of the switch when actuated.

In' order to apprise those skilled in the art how to construct and practice my invention, I shall now describe a preferred embodiment thereof in connection with the accom anying drawings which form a part hereo v:

In the drawings: l

Figure 1 is a front elevational view of an enclosed switch embodying my invention, the cover of the switch being broken away to show the relation of the interlocking ments are positioned as they are when the cover is closed and the switch is open;

Fig. 4 shows the interlocking elements as they appear when the cover is closed and the switch is closed;

Fig. 5 illustrates the position of the interlocking elements and relay connection when both the cover and the switch are open;

Fig. 6 illustrates the interlocking elements and relay connection as rendered inoperative by a key, the switch'having been closed while the cover remained open;

' Fig. 7 isa top plan view ofthe relay cony l nection;

Fig. 8 is a detail view of the inner side of thelost motion connection between the switchv and switch handle;

Fig. 9 illustrates the key employed to disable the interlocking mechanism;

Fig. 1() is a plan sectional view of the unitary casing containing the interlocking mechanism` showing the manner in which the key engages the various controlling elements; @Figa 11 is a side elevational view showing a. cover latch associated with the interlocking elements of the switch, the latch in this figure being locked permanently in cover securing position;-

Fig. 12 is another view similar to Fig. 11 and showing the same elements as formerly shown except that the cover latch in the last figure is in unlocked condition;

Fig. 13 is a fragmentary end elevational sectional view of some of the elements shown in Fig. 12 and illustrates the elements whereby an accidental locking of the cover latch is prevented; and

Fig. 14 is a slide elevational view of another form of switch box wherein my improved unitary locking and interlocking cover control means may be positioned.

The switch which 1 have shown as embodying my invention 1s preferably of a larger capacity type than the one shown in said -copending application, the operating elements of the present switch ybeing of heavier construction and consequently having greater inertia. However, there" is no particular capacity of switch to which my invention may be especially adapted, being on the contrary capable of embodiment in a switch of any capacity, I desire to state, however,

that in practical contemplate embodying the relay connections, constituting the essence ofthe present invention, more particularly in switches of capacities of 200 amperes or over. This is due to the fact that in switches of such capacities it is necessary to make the moving parts of greater weight and larger size in order to properly carry the current.

This increase in weight and size permits suficient force to be placed in back of the eort to close the switch While locked in open position,l so that permanent disablement or jamming of the interlocking mechanism is possibleif employed alone. The relay connections are, therefore, provided to carry the excessive load resulting from this attempt to force the' switch closed while the cover is open. I wish it to be understood that the material.

relay connections may be embodied in switches of any capacity, and therefore, do not limit myself yto any size or capacity of switches. y

Referring more particularly to the drawings, a. switch .box 5 is provided with a hinged cover 6. Disposed in the interior of the box 5, and' upon the back walls thereof, are a pluv rality of base units 7 for properly carrying 'the switch contacts. The base units 7 are individually secured to the back wall of the switch box 5 by means of screws 8 which pass through opposite flanges 9 on these base units and enter the back wall of the switch box. The base units 7 are preferably of insulation The advantages oflthis unit base construcv tion are more fully .described and specifically claimed in the copending application of Ali bert P. Ball, Serial No. 623,356, tiled March 7, 1923, for Unit base construction, the same being assigned to the Square D Company.

On these base units 7 are mounted switch contact clips 10, which are bridged by a movable contact 11, the latter being actuated by a switch operating handle 17, Which lies on the exterior of the switch box and connects to said movable contact 11 through a lost motion connection which will be presently described.

Referring more particularly to Fig. 8, a rigid base 15 carries a vertical plate 16, rigidly secured thereto, which plate 16 serves as a journal for the innerend ofA switch handle 17, the side wall of the switch box serving as a second point of support for this handle. Loosely mounted on the handle 17 is a member 18, preferably disposed between the side wall of the cabinet and the short end of the bail member to which the movable contact 11 is connected. Right angular lugs 19 and 2O are provided on the member 18 and are of such length as to lie in the path of movement of the bail member and a finger 21 fixed to the handle 17. As shown in Fig. 8, a pair cftoggle rods is arranged, preferably one on each side of the member 18, to provide a quick make and break action to the o ening and closing of the switch. On the right of member 18', a rod`2-1 is loosely pinned thereto, with the opposite end projecting through and being confined in the opening in the rigidly secured plate I26. A coil spring 25 encircles rod 24, being confined between the lost motion plate 18 and the rigid plate 26. On the opposite side of this plate 18 -a similar rod 27 is disposed, being also loosely pinned to plate 18, but, in this instance, serving as a connection betweenswitch operating mechanism and the interlocking mechanism 30, which will hereinafter be described. A coil spring 28 surrounds the rod 27 having one end confined at the point where the rod is loosely pinned tothe member 18, and the other end confined against one -side of the housing in which the parts of the interlocking mechanism 30 is disposed. The springs 25 and 28 are adapted for compression and expansion at various predetermined times during the opening and closing movement of the switch operating mechanism, whereby a quick make and break is provided between ,10. By providing these springs 25 and 28, a double spring toggle is obtained. During the initial movementof the switch handle 17,

the springs are compressed. As soon asl the movable blade 11 and the switch contacts i Y the lost motion connection between the switch y handle 17 and the switch.

The inner end ofthe handle 17 is preferably cut rectangular, and upon this rectangularend the linger 21 is fixed. Finger 2 1 is adapted to move between the projecting lugs 19 and 2O on the lost motion plate 18. It is to be noted that the side arm of the bail member 31 is confined between finger 21 and lost motion plate 18. This end' of the bail member 31 is loosely journaled around the inner end of the switch handle 17. In the operation of the-switch, this end of the switch handle 17 will bring the linger 21 into engagelnent either with the lug 19 or with the lug 20, as the case may be, and move the lost motion plate 18 against the tension of the springs .and 28 until these springs have moved past their dead center position wheremember 31.

upon the acceleratng movement caused by the springs' will quickly bring the opposite lug 19 or 2O into engagement with the bail Thusthe switch is forced quick- 'i ly to make or break Contact.'

l be readily opened withone finger lof the hand yA finger hold 35 is mounted on the topof the vhinged cover 6, whereby said-cover may while another finger thereof presses back a spring latch 36. We find that this'close relation of the two elements just mentioned is very convenient. `AA member 37 is vfastened to the inner side of the cover andis apertured to constitute4 a cover hasp. i y

' Asclear'ly. shown in Figs. 1 and 2, a housing 38, which contains the interlockingelements, and if desired, the cover latch 36, 1s of such a shape that it may bepositioned anywherein the switch box and occupy a negligible amount of space within the box. This housing is provided with a plurality of perforations: one designated 40 through which the cover latch 36 extends, anotherY designated 41 through which the hasp 37 extends finto operative relation with the elements within the Ahousing when the cover is closed, still another designated 42 in the end of the that portion of the'switch operating mecha- An ism which is operatively associated with thelinterlocking elementK within the housing-in this case bein-g the toggle rod 27- and .onedesignated L43-which is a key hole through which a propel` key may be inserted box` is apertured at44 whereby, when the for the purpose of disablingV the interloclb.

ing mechanism 30, as will be later described. It should benoted that the side of the switch housing is properly positioned, said aperture 44 registers with `the key aperture 43 in thezhousing. Bolts45 pass through the wall of the switch box and the housing and serve i to hold, in detachable relation, the housing in correct position with respect'to the-ele'- ments which are to be interlockedg. i i. A cover llock member 46 is pivotally mountportion 48, and on the other side o its pivotal point with anabutment portion 49. It is urged to the ri ht, or into locking position, by one arm 50 o the coil spring 52, the latter being wound around the pivoted pin 47.

A cam member 53, also 4pivotally mounted on the pin 47, is urged upwardly by another arm 54 of the spring 52. In its locking posi-v tion, that is, when urged upwardly to the limit of its movement in that direction, a reentrant portion 55 thereof engages the hook end 56 of the toggle rod 27 and revents its movement. Figs. 4 and 5 best il ustrate the manner` in which the toggle rod of the switch operating member is locked. Member53 is 4also provided, on the other side of its pivotal point from the reentrant portion 55, with an abutment portion 58. i-

A member 59 functions both as a protective cam at certain times during. the operation ofthe switch and as a controlling member forl the cam member 53. This member 59 is pivotally mounted on a pin61, and is l normally urged into the position of Fig. 6y

by the action of the coil spring 62, one arm 63l of whichengages around the portion 64 of the member 59. This member is also provided with a portion 65 which, it will be observed in Figs. -5 and 6, is positioned. di-

rectly beneath the aperture 41 through which the hasp 37 enters the housing while :the cover 6 is open/ A guide member 66 is'positioned as shown.

Between the bracket member68 and the 72, which are adapted, when said key is turned, to .engage the members 46 and. 53, respectively, to turn them about their pivots nagainst the action of spring 52, and thereby render their locking function ineffective. housing through which is adapted to pass 'scribe first the operation of the interlocking mechanism 30..

n Attention is first directed to Fig. 3 where- 111 the position of the various elements when the cover is closed, but-with the switch still open, is illustrated. Thisfigure should be considered in connection with Fig.4 5, theslatter showing the elements as they appear when the cover is open and before the switch is open. It will be noted that while the switch is in its open position, the hookportion 56 of the toggle rod presses against the abutment portion 49 of the member 46 and moves the y member 46 against the action of the lspring 52, so that the hook 48 disengages the 56 of the rod 27 willbe first moved to theright in the position shown in Fig. 5 and will thus strike the shoulder on the right hand side of the reentrant portion 55, whereby theA closing movement of the switch will be prevented. This action is clearly shown by the dotted lines illustrating the locus of movement ofthe end 56 on the toggle rod 27.

Considering now inFig. 3 the situation as existing after the cover has been closed, it should be first understood that as the cover closes, the hasp 37 passes'through the aperture 41 and the lower edge thereof presses against the upper edge of portion 64 of the member 59, pushing the latter downwardly to the left around pivot 6l against the action of the spring 62. As the member 59 turns and the portion moves downwardly, the portion 64 swings to the left and enters the aperture 75 in the hasp 37. It should be noted that the free end of the portion 64 is turned at right anglesto the plane of the member 59, whereby a transverse obstruction extends across the housing and under the aperture 41 when the member 59 is swung downwardly to the left This provision is most advantageous since it prevents the insertion of a nail, wire', or other instrument to push the member 59 downwardly to effect a release of the interlock, this latter feature not yet having been described. That is, although an instrument may be introduced as far as the portion 65 to move the same slightl downwardly, it is obvious that as soon as tile portion 64 comes beneath the aperture 4i, it will at once block any further movement ot' said instrument thus introduced.

Considering further the action of the portion 65 as it moves downwardly, I find that it comes in contact with the abutment portion 58 of the cam member 53, and since they are coplanar, the edge to edge engagement `of said members 59 and 53 serves to move the member53 downwardly against the action of the spring 52. lWhen the downward Inovement of the member has been a(':compl ished, it will be observed, as clearly shown in Fig. 3, that the reentrant portion 55 no longer engages the end 56 of the toggle rod, and the lat .A ter is, therefore, free to move along its locus,

in Fig. 4. It should be observed first, however, that in Fig. 3 the hook'48 has not enf tered'the aperture 75`of the hasp 37, the normal action o`f the' spring being opposed by the positive engagement of the toggle end 56 with the abutment portion 49 of the member 46. However, as the toggle rod moves away from the abutment portion 49, that is, as soon as the switch is moved to its closed position, the spring arm 50 urges the hook 48 into engagement with the hasp 37. This position is shown in Fig. 4, whekein it may be noted that the cover cannot be opened while the hooki48 extends fully into the aperture 75 of the hasp 37, and prevents the withdrawal of the latter from the exterior of the housing. At the same time, as hereinbefore indieated, the member 59 maintainsjmember 53 in its lower position, whereby the end of toggle rod 56 may freely travel through its locus as indicated in Fig. 4.

Assuming now, that with the cover closed and the switch closed, it is desired to open the cover without aecting the position of the switch contacts.- The manner in which this may be accomplished is illustrated in Fig. 6. The key 70 is inserted through the key hole and it is, of course, understoodthat l contemplate providing a key of particular formation having wards thereon, so shaped and positionedthat only a key which conforms to all of the required settings may be used. After inserting the key, the same is turned to the left, whereupon the ward portion 71 engages the edge of the vmember 46 and presses it to the left. then be withdrawn from the interior of the housing and the cover op'ened. If, on the other hand, the cover is open and the switch is likewise open, the key may be utilized to disable the interlock and permit the closing ofthe switch while the cover is open. With the switch as shown in Fig. 5, the key is inserted and upon being turned to the left, ward 72 thereof presses against a portion 72a o f the member 53 and turnsthe latter down-A wardly to the right whereby the toggle end 56. is released from the reentrant portion 55. The switch operating mechanism may then be moved toy switch closing position since there is no longer any obstruction in the path of movement of the toggle rod 27.

From the foregoing it will be observed that access to the interior f the switch box 5 while the switch is closed may be had only when the attendant has been provided with key 70 to disable the interlocking mechanism 30. If he has no key, thcnhaccess to the interior of the switch box is possible only when the switch has been opened to release the cover. It is -v The hasp 37 may.

experience that unauthorizedv persons in some rcases, may be able to apply such force to the handle as will cause the toggle rod to bend,

or the interlocking mechanism to jam by the end 56 of the toggle'pressing against the shoulder 55 with such force as to overcome the action of spring 52.A However, this is true only in those switches where the operating parts are of suiiicient size to permit the application of such a force. It is apparent that in smaller capacity switches, it is not possible to apply this force, and therefore, the interlocking mechanism and toggle rod 27 'thereof are sufficient to protect the locking of the switch in open position while the cover is open. But, as hereinbefore stated, the moving parts of switches of 200 amperage capacity, and over, are large enough to transmit the aforesaid force and cause destruction to nection 80`comprises a rod 81 having a pair of bell crank levers 82 and 83 at the ends thereof. Bell crank lever 82 is pivotally mounted on the lhorizontal portion 84 of the vertical plate 16,-as clearly shown in Fig. 7. According to the vdrawings,'this bell crank lever 1s disposed in a horizontal plane, and is adapted e to swing in the path of the lost motion plate 18 by engaging in the notch 85 cut m the lower edge of said lost motion plate. Bell crank lever 82 serves more particularly as a finger wedge and allows the plate 18 to be pressed thereagainst with as much force as can be applied through the switch handle 1n an attempt to close the switch while the.

cover is open. From Fig. -5 it will be seen that the upper edge of the groove 85 engages the top face of the bell crank lever 82. Thus a. surface engagement between these members is obtained, and consequently, it is practically impossible to destroyfthe finger wedge 82,

' much less is it impossible to cause it lto swing out of the path of the plate 18, as its movement is in a. plane at right angles to that of the plate 18. This is clearly shown 1n Fig. 7.

' f Bell crank lever 82 may be attached to the horizontal portion of the vertical plate 16 in any suitable manner, and the rod 81 may connect with the bell crank lever 82 in any preferable way. It is not essential that these attachments be such that disconnection of these members is impossible, for if the relay connection is disabled, the interlocking mechanism, as will be later seen, is still effective to prevent the closing of the switch. I have found that the circumstances underl which these switches are mutilated by jamming the interlocking mechanism are such that it does not warrent making the relay connection absolutely tamper-proof, because the workmen usually do not care to jeopardize their relation with their employer by suchacts.

The opposite end of the rod 81 is connected to the bell crank lever 83. Bell crank lever 83 is pivotally mounted at the side of the switch box by means of a pin 87, riveted at one end in the side of the switch box. The horizontal arm 88 of the bell crank lever 83 engages the lower edge of the switch lock member 53, being held thereagainst by means of a spring 89. One end of spring 89 connects to the lower arm of the bell crank lever 83, while the other end connects to a screw 91 projecting inwardly from the side of the switch box. Inasmuch as the bell crank lever 83 is at all times urged into engagement with the lower edge of the member 53, it will tend to follow said member in its movement. Referring now tothe operation of the relay connection 80, it will be seen from Figs. 3 and 7 that with the switch lock member 53 in its normal or upper position the bell crank lever 83 will also be in its -upper position, causing the rod 81 to swing the finger wedge 82 in the groove 85. This will prevent the switch handle from moving the lost motion plate 18 in switch closing direction. Thus it is impossible to close the switch. Two interlocks are thereby provided, one by the interlocking mechanism 30 and the other by this relayY connection 80, which is`controlled by the interlocking mechanism.

However, when the `cover is closed, as shown inFig. 3, the switch interlocking member 53 is forced downwardly by means of the member 59 swinging to the left and the portion 65 thereof engaging the abutmentv 58 and'forcing theJ switch lock member tothe right about its pivot 47. This movement of the switch lock member 53 forces the bell crank leverK 83 downwardly against the tension of the spring 89, thereby causing the rod 8l pivotally-to withdraw the finger wedge from without the groove 85. The lost motion plate 18 is then allowed to swing about its pivot to close the switch. f f

A shoulder 95 has been provided on the lost motion plate 18 for the purpose of serving as a stop member for the plate in its movement to switch closing position, the switch.v closing, of course, with considerable force as the result of the two toggle springs 25 and 28, and therefore requiring a stop to check the accelerating action imparted to it near the end of its movement. 'l'his will permit the switch blades 11 to engage the contacts 10 without placing an,v strain uponb the same. Likewise, when the switch is opened, the accelerating action of the lost ymotion plate 18 in its movement in this direction is checked byV a shoulder 96 on the plate which also serves as a stop member. In

' either case, therefore, the added force, re-

sulting from the double toggle mechanism and provided for the purpose of overcoming the increased inertia of lthe moving parts of the larger switches, does not tend to strain the switch structure, these stop shoulders serving to check the lost motion plate by engaging the horizontal portion 84 of the vertical plate 16..

. When the key 70 is employed to disable ythe interlocking mechanism 80, in order to close the switch while the cover is open, the action of the relay connection is substantially the same as hereinbefore described. Moving lthe key to the left, as shown in Fig. 6, causes the ward 72 to engage the switch lock memi ber53 and move it downwardly. The downward movement of the switch lock member 53 causes the bell crank lever 83 also to move downwardly, with the result that the linger wedge 82 iswithdrawn from the path of movement of the lost motion plate 18. The

switch may now be closed by movement yof the switch handle 17, the lost motion plate 18 which is mounted on the switch handle being allowed to turn without obstruction by the linger wedge or barrier lever 82.

While I have not elaborated on the action of the relay connection 80 when the coverl 6 is closed and the interlocking mechanism moved to permit the closing of the switch, it may be noted, however, that the relay connection `will be actuated by the closing of the cover, 'to withdraw the barrier lever 82 from the groove 85 in the lost motion plate 18. Thus both of the switch interlocks are4 the entire strain or load isplaced `upon lthe relay connection instead of the interlocking mechanism, when any attempt is made to force the switch closed while locked in open position, but here again I do not intend to limit myself to the specific structure shown. The groove or recess 85 cut in the lost motion plate 18 is slightly larger in a vertical di rection than the thickness of the barrier lever 82, so that the latter when actuated may easily slide within the former. Consequently a small space, being negligible however, is left between the top face of the barrier lever 82 and the lower edge of the plate 18. If so desired, this space may be omitted, but for mechanical reasons it is preferable. If `an attempt is now made to force the switch closed while the cover is open, the switch handle may be moved slightly until the lower edge of plate 18 strikes the top face of barrier lever 82. As shown in Fig. 6, the lever 82 is flatly supported upon the horizontal portion 84.- of plate 16 carried upon the rigid post 15, and therefore, can not be displaced. Hence the switch handle can not be moved any farther and attempts to jam the switch interlock are frustrated.

The interlocking function of the relay connection 80 acts in advance of that of the interlocking mechanism 30. This prevents any strain, resulting from attempts to force the switch closed, upon the interlocking mechanism.` By referring to Fig. 5 it will be seen that the end 56 of the toggle rod 27 is requiredto move a certain distance, in the reentrant, portion 55, before it engages shoulder on the switch lock member 53. This distance is slightly greater than the aforesaid space between the top face of barrier lever 82 and the lower edge of plate 18. Hence, the end 56 of toggle rod 27 will not engage shoulder 55 before the plate 18 engages barrier lever' 82, and the interlocking mechanism 30 will not be required, therefore, to carry said strain. This strain is placed upon the bar-rier lever 82 and the vertical post 15, and is not transmitted by the rod 81 to the interlocking mechanism.

In my aforesaid copending application, I have disclosed a spring cover latch which may be used to lock the switch box cover 6 permanently closed. This cover latch is mounted on .pin 61 of the disabling Ydevice and is operated by the key by turning it in a direction reversed to that required to disable the cover lock member 46 and the switch lock member 53. Although it has not been illustrated in the present instance, I wish it to be understood that this-permanent spring cover latch may be embodied in the present device and obtain all the advantages accruing4 from its use.

The aforesaid spring cover latch is an additional feature which has been demanded by the switch using public. I have found that there is an insistent demand for a positively latched cover in an enclosed switch. Furthermore, such demand is present'even though the switch in question may bev provided with an interlocking mechanism.

There are numerous reasons for this demand on the part of switch users--not the least of which is the wish to have permanently associated with the enclosed switch some device whereby the cover may be locked closed even though the switch is open. It will be remembered, ofcourse, that, in an interlocked switch of the character heretofore discussed,

`as soon as the switch is thrown to open position, the cover ma `be opened.

It appears pre erable therefore to incorporate at some point on thebody of the switch the interlocking and cover lat'ching features.

In order that the interlocking 'mechanism may function properly it is quite essential that the cover of the box close snugly thereupon, and I have found that a cover latch quite often interferes with the normal operation of the interlock. This'last occurs beca use of the natural lightness, and consequent tendency to spring, of the material of l l which the cover is made. Then again it is my desire, if the customer wishes a switch box having both the interlocking means and 4 the cover latch, to simplify the structure by associating these ytwo features in such mannersthat an extremely simple cover control will be eventuated.

In pursuance of this object I associate a cover latch with the interlocking mechanism in such manner that said latch may be posi- 'tively locked, when desired, bywthensame key which I-have heretofore mentioned as controlling the disablement or release of the in- Vterlock mechanism. By so lpositioning the latch and by -utilizing a key to effectuate the locking thereof, I eliminate altogether the bothersome padlocks which have been almost universally employed in permanently locking the covers of enclosed switches.

Having provided a structure wherein the same key may either disable the locking mechanism or'serve to lock the cover latch, I find that an additional feature is quite desirable. While the reason for this additional feature will be better understood after a reading of .the description of the switch itself, I may here state that somemeans must be provided which will prevent the inadvertent locking of the cover latch. I find, for instance, that when the switch box cover is open and an inspector has inserted the key for the purpose of releasing the switch operating mecha anism, he mayinadvertently so turn the key that the cover latch is locked. If'now the cover switch be slammed closed a destruction of the entire interlocking mechanism may occur. Then, too, if the locking latch is not utilized, or its use is not understood by thel inspector he may inadvertently lock the same and thereafter be unable to understand why he cannot close' the cover.

further object of my invention, therefore, is to provide means-whichwill positively prevent the inadvertent locking ofl the cover latch when it is only desired to disable thev interlock. Such means may be pertinently defined as selective means since their embodiment in the switch necessitates a definite selection between the two sets of locking or cover controlling elements-that is, theoperator must definitely select either the permanent latch feature as controlling the cover movement, o he may desire to depend on the interlocking mechanism for the control of the movement of the cover. Therefore, I hereafter refer to the key and its associated mechanism as the means whereby the particular type of cover control which the operator desires is selected.

or not. That is, I propose'to embody my invention in a device of such character that it can be applied to switches which are already installed if the userofV the latter desires to availhimself of the advantages which are incident to the embodiment of my interlock It is my further desire to provlde an interin an enclosed switch. I, therefore, embody l my interlock and, if desired, my cover locking latch, in a unitary structure which may be readily applied to most enclosed switches without altering in any manner the' essential and fundamental elements of the switch operating mechanism. With this object in view I dispose my interlocking mechanism, as well as the, cover latch if desired, in a housing which may be-applied to substantiall all enclosed switches. Of course, it shou dl be understood that, conversely, if for any reason/it is desired to remove'the interlocking feature entirely from those switches in which it is initially furnished this can be done quite simply and expeditiously since the unitary construction of my mechanism enables it to be either applied to, or removed from, .a switch box with a minimum effort and altera-A tion of the switch.

In conformity with the above desire to provide a selective cover` controllin system, I providethe structure shown in 13 and 14 which latter embody, together with all the other desirable interlocking features heretofore discussed, a cover latch which is normally spring operated and by means of which the cover may be permanently locked shut, irrespective of the position of the switch operating "elements, It will be understood, of course, that `this latch may -be included igs. 11, 12,`

when the customer so desires, or it may be omitted. In case it is desired I wish todi- In Fig. 11 the cover latch 36 is pivotally v mounted on the pin 61, and after passing through an aperture 6a on the cover is urged into locking position by the arm 63a of the spring passing around the pin 61. This latch 36 is faced as shown in order that if the cover is closed, the latch may be pushed to the left, the reentrant portion 362 of the latch engaging the cover after the latter has been completely closed, this by reason of the fact that said latch is constantly urged to the right. The latch 36 is provided with adownwardly extending portion 36a, which portion moves to the right as the upper end of the latch is pressed to the left.

' Rotatably mounted on the key cylinder 69 is a locking member or discf69a which is provided with a hooked locking portion 696, itv

being understood that the latch 36 and the disc 69a lie in the same plane wherefrom the hook 691) engages the extreme lower end of the portion 36a and holds the latch in locked relation with the cover when said elements are engaged as shown .in Fig. 11.

It willA be observed that this locking disc 69a',y may be turned into locking position (as shown in Fig. 11) by turning the key 7 0 approximately o to the right. The said disc 69a is provided with pits or openings 69o which,r receive a ratchet point 69d mounted on a springmember 69e. The latter member 69e is secured to the wall of the housing and is so tensioned that the point 69d is constantly urged toward and into the openings 69o in the member 69a. Because of this latter construction, an appreciable twist is required to locking of the latch in its extreme right-hand position'. I have, therefore, provided means which insure against such inadvertent lockin l' spring member 69]e is mounted on the wall of the housing (see Figs. 12 and 13) and has its lower 'end 69g normally positioned to engage the hook portion 69?) and prevent the movement of the locking disc 69a to the right.

A push button 69h extends through the wall of the switch box and provides means whereby the spring 69f can be moved inwardly (to the left in Fig. 13) to disengage they lower end 69g and the hook 695.

When the operator has deliberately and 05 positively pushed button 69h and effected the disengagement of the hook 696 from the lower end 69g of the spring member 69f, such operator may then turn the key to the right whereupon the hook 69.7) will travel upwardly and engage the lower end 36a of the latch 36, as shown in Fig. 11, whereby said latch 36 is locked in its cover latching position. To obtain access to the switch enclosure, it will now be necessary to insert the key in the keyhole 40 and turn said key 30 to the left whereupon the cover latch 36 will be released and the cover control mechanism of the interlock will be restored to its normal position.

It will be understood, therefore, that I have provided means which require that the operator of the switch knowingly select the particular type of cover control which he desires. This selection is made easy since the same key is utilized for both kinds of cover control; merely the reversal of direction inl the twist being necessary to'change the enclosed switch from one inwhich the cover n is controlled only by a latch to one wherein the interlocking feature predominates. Even thoughI have associated this last described latching feature with my device, I have rendered it no less unitary and capable of application to bothold and new enclosed switches. I believe I am the first to appreciate the necessity for supplying the increasing demand for safety switches and at the same time reconciling the various apparent diverse requirements of the users of this switch.

As pointed out in the foregoing description, I have provided an enclosed switch locking aggregate which makes available to the user any of a number of methods of cover control. Moreover, I have made the selection of the desired type of control quite easy whereby the user is enabled to select the desired control by merely turning a key. And finally I feel that the provision of means whereby the selection must be made, positively removes the only chance which there might be of inexperienced operators inadvertently causing an undesirable type of cover control to function. As above indicated, the advantages incident to the varied cover control system are made available to users of old style switches as well as to those who initially adopt my switch. This change is made easy because of my unitary detac able construction.

l'In Fig. 2, an apertured member 90 having an aperture therein projects through an opening in the cover 6 from the interior of the switch box 5. If so desired, a padlock (not4 shown) may be used to lock the cover permanently closed.

As I have hereinbefore pointed out, the

the type shown herein as would separate these interlocks and have them operate independently, inasmuch as I intend primarily to provide a device for preventing the jamming or rupturing of the standard interlocking mechanism on switches of larger capacity. Likewise it would extend to a structure wherein these interlocks might be operated individually by cover hasps similar to hasp 87 on cover 6, and also be disabled by individual disabling devices.

Though I have described with great particularity of detail a preferred embodiment of my invention, yet it is not to be understood therefrom that the invention is restricted to the specific embodiment described. Various modifications thereof, in detail and in the arrangements of the parts may be made by those skilled in the art, without departing from the spirit and scope of the invention.

Iclaim:

1. In combination with a switch box having a cover thereon and .switch operating mechanism therein, aninterlocking mechanism whereby the cover can not be opened while the switch is closed nor the switchl closed while the cover is open, a housing in which said mechanism is disposed, and a relay connection exterior of said housing but cooperating with said interlocking mechanism and said switch operating mechanism for also preventing the closing of the switch while the cover is open.

2. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism, a connection between said interlocking mechanism and said switch operating mechanism, Aand a second connection controlled by said interlocking mechanism for interposing a barrier in the path of said switch operating mechanism while said cover is open.

3. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the covercan not be opened while the switch is. closed nor the switch closed .while the cover is open, a housing in which said mechanism is disposed, a relay connection between said switch operating mechanism and said interlocking mechanism for relieving the latter of any strain as the result of an attempt to force said switch closed while the cover is open, said connection cooperating with said interlocking mechanism at one side of said housing.

4. In combination with a switch box having a cover thereon and switch operating mechanism therein, a pair of interlocks for said switch `operating mechanism whereby the switch can not be closed while the cover the other interlock and receiving the strain resulting from an attempt to force said switch closed while the cover is open.

5. vIn combination with a switch box having a cover thereon and switch operating mechanism therein, a pair of interlocks for said switch operating mechanism whereby the switch can not be closed while the cover is open, one of said interlocks controlled by but preventing the permanent disablement of the other.

6. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover can not be opened while the switch is closed nor the switch closed while the cover is open, and means controlled by said interlocking mechanism and constituting a reinforcement for the interlock when holding the switch open while the cover is open.

7 In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism for preventing the closing of the switch while the cover is open, and means controlled by said interlocking mechanism for also locking the switch open while the cover is open, said means acting in advance of said interlocking'mechanism in order to prevent permanent disablement of the latter by an attempt to force the switch closed.-

8. In combination with a switch box having" a cover thereon and switch operating mechanism therein, an interlocking mechanism for preventing the closin of the switch while the cover is open, means tor also locking the switch open while the cover is open and functioning in advance of tlie locking action of said interlocking mechanism in order to prevent the permanent disablement of the same by an attempt to force the switch closed, said means including a pivotally mounted member, said member being urged into enspring urged member engaging a portion of 'said interlocking mechanism.

10. In combination with a switch box having a cover thereon'aiid switch operating mechanism therein, an interlocking mechanism for preventing the closing of the switch while the cover is open and including a switch locking member, additional means for also preventing the closing of the switch while the cover is open, said means including a spring urged member adapted to engage said switch locking'fmember and be controlled thereby.

- 11'. In combination with a switch box hav- A ing a cover thereon and switch operating mechanism therein, an interlocking mechanism for preventing the closing of the switch while the cover is open, additional means for preventing the closing of the switch While the cover is open, said switch operating mechanism being provided with a notch therein, said means including a movable member adapted to lie in said notch'while the cover is open to prevent the closing movement of said switch operating mechanism.

12. In combination with a switch box having aj cover thereon and switch operating mechanism therein, an interlocking mechanism for preventing the closing of the switch while the cover -is open, a rod between said switch operating mechanism and interlocking mechanism, a barrier at one end of said rod, said rod being actuated by said interlocking mechanism to project said barrier in the path of said switch operating mechanism when said cover is open whereby a double interlock prevents the closing of the switch.

13. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism for preventing the closing of the switch while the cover is open, said mechanism embodying pivoted switch locking means for locking the switch closed through the medium of an element projecting from said operating mechanism. said switch locking means having an engageable surface and adapted when in normal position to lock said element whereby the switch is held in open position, a second element projecting from said switch operat- 1 ing mechanism and contacting with said engageable surface, said second element also Ifunctioning to interlock the switch in open position when said pivoted switch locking means moves to normal position.

14. vIn combination with a switch box having a cover thereon and switch operating i5 mechanism therein, an interlocking mechanism for preventing-.the closing of the switch while the cover is open, an element connected to said switch operating mechanism yand adapted Ato be engaged by a switch locking member normally urged into locking relation nism whereby the switch can not beclosed" lwhilev the coverl is open, a toggle rodse'rving as a connection between said switch operating mechanism and said interlocking mechapivotally mounted arm at each end of saidVY second rod.

17 In combination with a switch boxhaving a cover thereon and switch operating mechanism therein, an interlocking mechanisin whereby the switch can not be closed while the cover is open, a rod serving as a connection between said vswitch operating mechanism and said interlocking mechanism, a second rod between said mechanisms, and

pivotally mounted bell crank arms connected at each end ot said second'rod for cooperation with said switch operating mechanism and said interlocking mechanism.

18. In combination with a switch box having a lcover thereon and switch operating l mechanismV therein, an interlocking mechanism tetweeii said cover and said switch operating mechanism whereby the switch can not be closed while the cover is open, means for providing a second lockfor said switch operating mechanism in order to prevent disablement of said interlocking mechanism upon an attempt to force said switch closed, said means comprising a connecting member. having a pivotally mounted member at each end, one of said members adapted to serve as a barrier to prevent the movement of said switch operating member, the other member controlling the position of the first mem-` ber and cooperating with said-interlocking member.

19. In combination with a switch boX having a cover thereon and switch operating mechanism therein, an interlocking mechanisnibetweeii said cover andL said switch operating mechanism whereby the switch can not be closed while the cover is open, means for providing a second lock for said switch operating mechanism in order to prevent the disablement of. said interlocking mechanism, said meansv being controlled by said interlocking mechanism and being simultaneously effective therewith, said means including pivo'tally mounted members, one serving as a barrier member and the other as a controlling member.

20. In con'ibinati'on with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism between said cover and said switch' operating mechanism whereby the switch can not be closed while the cover is open, means for providing a second lock Jfor said switch operating mechanism in order to prevent the disablement of said interlocking mechanism, said means being controlled by said .interlocking mechanism and being effective when the latter is effective, said means coinprising a connecting member having pivotally mounted'members at the ends thereof, one serving as a barrier member adapted for A projection in the path of said switch operating mechanism by the actuation of the other member which is arranged to cooperate with said interlocking mechanism.

21. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism between said cover and said switch opeating mechanism whereby the switch can not be closed while the cover is open, means controlled by said interlocking mechanism for strengthening the locking action of the latter and thereby preventing a forced closure of the switch while the cover is open, said means comprising a connection between said switch operating mechanism and said interlocking mechanism. said connection having a spring urged member. adapted to engage a portion of said interlocking mechanism and be operated thereby in order to actuate said means accordingvto the condition of the interlocking mechanism.

22. In combination with a switch box hav- -ing acover thereon and switch operating mechanism therein, an interlocking mechanism between said cover -and said switch operating mechanism whereby the switch can not be closed while the cover is open, a relay connection for reinforcing the interlock by engaging and preventing the movement of said switch operating mechanism while the cover is open` said relav connection including apivotally mounted finger member disposed substantially at right angles to said switch operating member and adapted to lie in the'path of the latter.

23. In combination with a switch box having :i cover thereon and switch operating mechanism therein, an interlocking mechanism between said cover and said switch operating mechanism whereby the switch can not be` closed 'while the cover is open, a relay connection for reinforcing the interlock by engaging and preventing the movement of said switchoperating mechanism while thel ing a cover thereon and switch operating mechanism therein, an interlocking mechanism for preventing the closing of the switch while the cover is open, a relay connection actuated by said interlocking mechanism whereby an attempt to force the switch closed while the cover is open is prevented, said relay connection being simultaneously effective with said interlocking mechanism to lock said switch in-open position, said interlocking mechanism remaining effective although said relay connection may be disconnected.

25. In combination a switch boX having a cover thereon and switch operating mechanism therein, an interlocking mechanism for preventing the closing of the switch while the coveris open, a relay connection actuated by said-interlocking mechanism whereby an attempt to force the switch closed while the cover is open is prevented, said relay connection adapted to operate simultaneously with said interlocking mechanism, a housing for enclosing said interlocking mechanism and preventing disablement thereof, said connection cooperating with said interlocking mechanism at one side thereof whereby disabling said connection will not disable theinterlocking mechanism.

26. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism for preventing the closing of the switch while the cover is open, a relay connection between the switch and interlocking mechanism also functioning to prevent the closing ofthe switch while the cover is open, and means for rendering said interlocking mechanism and said relay connection ineffective.

27. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism between said switch operating mechanism and said cover, a relay connection between saidswitch operating mechanism and said interlocking mechanism whereby the switch can not be closed while the coveris open, and means for rendering said relay connection ineffective.

28. In combination with a switch having -a cover thereon and switch operating mechanism therein, an interlocking mechanism between said switch operating mechanism and lsaid cover, a relay connection between said switch operating mechanism yand said interlocking mechanism and controlled by the` latter whereby the switch can not be closed vwhile the cover is open, and disabling means for rendering said relay connection ineffectiv. 4

29. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism between said switch operating mechanism and said cover, a relay connection between said switch operating mechanism and said interlocking mechanism whereby the switch can not be closed while the cover is open, and key controlled means for rendering \said relay connection ineffective.

30. In combination with a switch having a cover thereon and switch operating mechanism therein, an interlocking mechanism between said switch operating mechanism and said cover, arelay connection between said switch operating mechanism and said interlocking mechanism and controlled by the latter whereby the switch can not be closed while the cover is open, and key controlled means for rendering said relay connection ineffective through said interlocking mechanism.

31. In combination with a switch having a cover thereon and switch operating mechavnism therein, an interlocking mechanism the switch is open, said interlocking mechanism embodying a switch locking member for locking the switch open while the cover is open, means actuated by sald swltch locking member for also locking the switch open while the cover is open, and key-like means for rendering said switch locks ineffective.

33. In combination with a switch having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover can not be closed while .the switch is open, said interlocking mechanism embodying a switch locking memberfor locking the switch open while the cover is open, a connection between said switch operating mechanism and said interlocking mechanism, said conn ection being operated by said switch locking member and providing an additional lock for the switch, and means for rendering said switch locking member and said connection ineffective. i

34. In combination with a switch having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover can not be closed while the switch is open, said interlocking mechanism embodying a switch locking member for locking the-switch open while the cover is open, means controlled by said switch locking memfber for also locking the switch open while the cover is open, means operated by the closure of sald cover. for rendering said switch locking member and first said means ineffective, and means for moving when desired said switch locking member and first said means for nullifying their locking functions.

35. In combination with a switch having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover can not be opened while the switch is closed nor the switch closed while the cover is open, said mechanism embodying cover locking means to lock said cover closed while the switch is closed, switch locking means for locking the switch open while the cover is open, a second interlocking mechanism controlled by said first interlocking means, and means for rendering said cover locking means and said switch locking means ineffective to nullify their locking function and the locking function of said second interlocking mechanism.

36. In combination, an enclosed switch provided with a movable cover and means affording an interlock for preventing the independent manipulation of the switch and cover, and means affording a second interlock reinforcing said first interlock and for also preventing the closing of the switch while the cover is open. v

37. In combination, an enclosed switch provided with a movable cover and means affording an interlock for preventin the independent manipulation of the switc and cover, and means affording a second interlock reinforcing said first interlock and for also preventing the closing of the switch while s the cover is open, and means for disabling both of said interlocks.

38. An enclosed switch having a cover thereon and switch operating mechanism therein, interlocking mechanism for preventing the opening of the cover while the switch is closed and for preventing the closing ofthe switch while the cover is open, and relay means associable with said interlocking mechanism for removing the strain from the latter when it is sought to force said switch closed while said cover is open.

39. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, said mechanism embodying cover locking means to positively lock said cover closed while the switch is closed, switch locking means for locking the switch open while the cover is open, means operated by the closure of said cover to render said switch locking means ineffective, means comprising a key having portions adapted to engage both said cover locking means and c lwhile the switch is closed nor the switch closed while the cover is open, said .mechanism embodying pivoted cover locking means to positively lock said cover closed while the switch is closed, pivoted switch locking means for locking theswitch open while the cover is open, pivoted means operated by the closure of said cover to render 4said switch locking means ineective, and means for moving, when desired, both said cover locking means and said switch locking means to nullify their locking functions comprising a key having portions adapted to move both said cover locking means and said switch locking means around their pivots to nullify the locking functions of the latter two elements.

41. In combination with a switch box having a' cover thereon and switch operating t mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, said,- mechanism embodying cover locking means, a hasp on said cover which is engaged by said cover locking means when the cover is closed to lock said cover in the latter position, said cover locking means being moved to unlocking posi- `tion by the opening of said switch, switch locking means which prevents the switch closing movement of said switch operating mechanism when the cover is open, both orn said locking means having a common pivotal mounting and a common spring so engaging said locking means that they are both normally urged into locking position.

42. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switchis closed nor the switch closed while the cover is open, said mechanism embodying cover locking means, a hasp on said cover which is engaged by said cover locking means, when the cover is closed, to lock said cover in the latter position, said cover locking means being moved to unlocking position by the opening of said switch, switch locking means/ which prevents the switch closing movement of said switch operating mechanism when the cover is open, both of said locking means having a common pivotal mounting, a common spring so engaging said locking means that they are both normally urged into locking position, and a key adapted to engage both of said locking means to move them against said spring whereby their normal locking function is nullitied.

43. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a cover`v latch, and means coacting with both the interlock and the latch for permitting the use of either the interlock or the latch.

44. In combination with a switch boxhaving al cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a cover latch, and means coacting with both said interlock and latch for permitting the use of either the interlock or the latch, or both.

45. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed w-hile the cover is open, a cover latch, and a member operable to disable said interlocking mechanism by interiitting connection with portions of the latter, said member being also used for locking said cover latch to hold said cover closed.

46. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened whi le the switch is closed nor the switch closed while the cover is open, a cover latch, and means comprising locking members and a key operating the same for locking said cover latch to hold said cover closed, said key also cooperating with the interlocking mechanism to nullify the interlock when desired.

47. In combination with a switch boX having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a cover latch, means comprising locking members and a key operating the same for locking said cover latch to hold said cover closed, said key also cooperating with the interlocking mechanism to nullify the interlock when desired, and-means for preventing an inadvertent locking of the latch.

48. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a cover latch, means for locking said cover latch to hold said cover closed, and means preventing the inadvertent means for locking said cover latch to hold said cover closed, and means preventing the inadvertent movement of said last named means to lock the latch during an interlock nullifying movement thereof.

50. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a cover latch, locking members for said latch, and means comprising a key engageable with said interlocking mechanism and said latch locking members which may be used either to lock said latch ordisable said interlock.

51. In combination with a switch box havlng a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a cover latch, means comprisingr a key which may be used either to lock said latch or disable said interlock, and means for insuring that said latch will not be inadvertently locked when it is intended to disable said interlock.

52. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the lswitch closed while the cover is open, a cover latch, means comprising a key which may be used either to lock said latch or disable said interlock, and means for'positively preventing the latch-locking movement of said key means except at predetermined times.

. 53. In combination with a switch box having a cover thereon and switch operating` mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a cover` latch, means comprising a key which may be used either to lock said latch or disable said interlock, means for positively preventing the latch-locking movement of lsaid key means, except at predetermined times, and manually controlled means for permitting the latchlocking movement of said means when the operator so desires! 54. In combination with a switch box having a cover thereonand` switch operating mechanism therein, an interlockingr mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cov-er is open, apivoted cover latch associated in unitary relation with said interlocking mechanisml and which is normallyurged into cover locking position but so constructed that the cover on closing may push the same aside and properly close, and means for positively locking said latch when desired.

55. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a pivoted cover latch associated in unitary relation with said interlocking mechanism and which is normally urged into cover locking position but so constructed that the cover on closing may push the same aside and properly close, and means comprising a key for positively locking said latch when desired.

56. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a cover latch, and means comprising locking members and Aa key for locking said latch. said latch and said interlocking mechanism being so associated that said key may also be used to disable said interlock when desired.

57. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking'meehanism whereby the cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a housing within which said mechanism is positioned and into which a-portion of said normal switch operating means may be projected for operative association with said interlock and also into which a portion of said cover may project for association with said interlock, and a cover latch positioned within said housing and projecting/therefrom.

58. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannotbeopened while the switch is closed nor the switch closed while the cover is open, a housing within which said mechanism is positioned and into which a portion of said normal switch operating means may be projected for operative association with said interlock and also into which a portion of said cover may project for association with said interlock, and a cover latch positioned within said housing and extending therefrom, said housing and its associated mechanism being removable as a unit from said switch box.

59. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the cover cannot be opened -while the switch is closed nor the switch closed while the cover is open, a housing within which said mechanism is positioned and into which a portion of said normal switch operating means may be projected for operative association with said interlock and also into which a portion of said ',cover may project for locking associationl with said interlock, and a cover latch positioned within said housing and projecting therefrom, said housing being removable from, and-connectible to, said switch box as a unit, and being capable of direct association with the normal switch operating mechanism in said box whereby the character of said switch may be readily altered.

60. In combination with a switch box having a cover thereon and switch operating mechanism therein, an interlocking mechanism whereby the `cover cannot be opened while the switch is closed nor the switch closed while the cover is open, a housing within which said mechanism is positioned and into which a portion of said normal switch operating means may bc projected for operative association with said interlock and also into which a portion of said cover may project ior association with said interlock, and a cover latch positioned within said housing and projecting therefrom, interlock and latch 1 controlling means, said housing and said box having registering openings to permit the entrance of said controlling meanstrom the outside of said box.

61. In combination with a switch box having a. cover thereon and a switch operating mechanism therein, an engageable member on said cover, an interlocking mechanism removable as a unit from said box comprising a cover locking member, a switch locking member, said members being pivotally mounted on a common support, means comprising a spring attached tosaid support and having two arms, one engaging each member, for normally urging said members into locking position, each of said members heilig provided with a hooked portion to engage selected elements` and means for moving said switch locking member into unlocking position as the cover is closed.

62. In combination with a switch box having a cover thereon and a switch operating mechanism therein, an engagcable hasp on said cover, an interlocking mechanism comprising a cover locking member. a r,switch member, means for normally urging said members into locking position, each oi said members being provided with a hooked portion to engage selected elements, means for moving said switch locking member into unlocking position as the cover is closed, and means comprising a key member insertible into operative association with the interlock 'from the exterior of said box Jfor moving said cover locking member from engagement with said hasp although the switch is closed and 'for moving said switch locking member out of engagement with said switch operating means although said cover is open, said'key comprising ward portions which severally engage said locking members to move them -from their locking positions.

(53. In combination with a switchbox having a cover thereon and a switch operating mechanism therein, an engageable hasp on said cover, ran interlocking mechanism comprising a cover locking member, a switch locking member, means for normally urging said members into locking position, each of said -members being provided with a hooked portion to engage selected elements, means for moving said switch locking member into unlocking position astthe cover is closed, means comprising a key member insertible into operative association with the interlock from the exterior of said box for moving said cover locking member from engagement Y with said hasp although the switch is closed, and for moving said switch locking member outof engagement with said switch opera"- ing means although said cover is open, said key comprising ward portions which severally engage said locking members to move them from their locking positions, and means to prevent all keys but the proper one from affecting said interlock.

64. In combination with a switch box having a coverlthereon and a switch operating mechanism therein, an engageable member on said cover, interlocking mechanism comprising a cover locking member cooperating with said engageable member, a switch locking member for preventing movement of said switch operating means, said members being normally urged towards locking position, a latch adapted to normally engage said cover but being yieldable to allow said cover to open and close, said latch being associatedV with said interlocking mechanism, and means comprising a key for locking said latch, when desired.

65. In a switch box having a`cover thereon and a switch operating mechanism therein, an engageable member on said cover, interlocking mechanism comprising a cover locking member cooperating with said engageable member, a switch locking member for preventing movement ofsaid switch operating means, said members being normally urgedl towards locking position, a latch adapted to normally engage said cover but being yieldable to allow said cover to open and close, said latch being associated with said interlocking mechanism, and means comprising a key for locking said latch or for disabling said locking members.

66. In a switch box having a. cover thereon and a switch operating mechanism therein, an engageable member on. said cover, an interlocking mechanism comprising a cover locking member cooperating with said engageable member, a switch locking memberv for preventing movement of said switch operating means, said members being normally urged towards locking position, a latch adapted to normally engage said cover but heilig yieldable to allow said cover to open and close, said latch being associated with 

